1. Field of the Invention
The present invention relates to a technique for correcting a camera shake of an image sensing device.
2. Description of the Related Art
A human brain can perceive depth by the disparity between images captured by the left and right eyes. That is, a human can perceive three dimension when images having disparity are presented to the left and right eyes. Therefore, binocular stereoptical image presenting techniques (stereopsis) using a polarization method, liquid crystal shutter method, and the like are known.
To generate a left-eye image and right-eye image for binocular stereopsis, a method of sensing images by using two image sensing devices spaced apart by the eye separation or a method using 3D computer graphics rendered by moving the viewpoint position has conventionally been used. An apparatus adopting the former image sensing method using two image sensing devices is large in size and has not been manufactured as a household product. However, as the number of pixels of an image sensor is increased and the sensor itself is downsized, the binocular stereoptical image sensing device has been downsized. Recently, an image sensing device including two image sensing optical systems has been developed as a household digital camera or the like. Accordingly, users can sense binocular stereoptical images in hand carried devices in the same manner as when they use general image sensing devices.
When viewing a binocular stereoptical moving image sensed by a hand carried device as described above, a viewer sometimes feels fatigued because image blurring due to camera shake or the like during image sensing or a frequent change in gaze point causes so-called “3D sickness”. Japanese Paten Laid-Open No. 07-043647 has disclosed a technique for correcting image “blurring” in the horizontal and vertical directions in a plane perpendicular to the optical axis of an optical apparatus including two optical systems such as a binocular.
In hand-carry image sensing, however, image “blurring” due to rotation around the optical axis sometimes occurs in addition to the horizontal and vertical camera shakes described in Japanese Patent Laid-Open No. 07-043647. In the image sensing device using two image sensing optical systems, however, the following problem arises if the conventional method of cropping a rectangular region by rotating a sensed image in order to correct image “blurring” in the rotational direction is used. If rotation occurs around the optical axis of the image sensing device using two image sensing optical systems, the distances between the rotation center and image sensors of the two image sensing optical systems are different. Therefore, a position in an image obtained by sensing a given object differs from that in an image obtained by sensing the same object with no rotation. That is, binocular stereopsis fails if simply rotated images are used.